Tire mold



Patented Aug. 9, 1927.

UNITED STAT-Es PATENTl OFFICE.

vHARRY WILLSHAW, OF BUFFALO, NEWYORK, ASSIGNOB T0 DUNLOBTIRE AND RUB*-BER CORPORATION OF AMERICA, OF BUFFALO, NEW YORK, A CORPORATION OF NEWYoan.

Application filed October 13, 1.924. Serial No. 743,184.

This invention relates in general to molds and in particular toimprovements in molds used for the manufacture of rubber tires and themethod of producing such molds. The invention will be understood fromthe f'ollowing specification when read in connectlon with theaccompanying drawings in which Fig. l is 'an end elevation of a moldmade according to my invention and embodying features of noveltyhereinafter/more fully pointed out.

- Fig. 2 is lan. enlarged transverse sectlon through the mold, takenons'line 2-'2 of Fi 1.

lgig. 3 is la face view of aportion of a steel shell forming part of themold.

Fig. 4 is a face view of a" portion, of a tread ring forming art ofthelmold.

Fig. 5 is a parta plan view ofl a tire the treadof which is formed bythe mold shown in the above gures. l

Referrin in detail tothe drawings, the mold inclu es a bottom ring ormold section 10 and a top rin or mold section 12, which parts are formewith inwardly extending flanges 14 and 16 for engagement with a ring 18.The latterforms a bearing for the metallic base band 2O voi arubbertireof the solidl or semisolid t' pe such as indicated at 22 which isadapted7 to be formed and vulcanized in the moldforming the subjectmatter of my invention. The mold sections 10 and 12 are each formed withsui-table recess and at spaced intervals around the periphery inserts orsid pieces 26 are secured .in the recesses in th respective moldsections in order to form indentations in the side walls of the tire.These inserts are preferably made of a metal or metal alloy containinaluminum, magnesium, manganese, chro-` mium and copper which can beeasily/cast with a very smooth surface of extremely fine grain. Theinserts or-side pieces may be welded, screwed or otherwise 'secured tothe molded sections, and'while I have used the term inserts, it is to beunderstood that they are notv necessarily seated in sockets formed inthe molded sections.

The tread portion of the tire 22 is molded or shaped -b a tread ring28-which is formed with suitab e pro'ections 30 shaped and proportionedto pro uce the desired' .configuration of tire tread design. Theseprojections are of necessity in many cases irregular in shape. Thedesign and arrangement of the` projections, of course, varies with thearticular type of tire tread to be produced. Heretofore it has been thepractice to form lsuch treadmold projections by machining them to thedesired shape. This entails expensive profiling operations and 'oftencalls for the provision of master patterns or teniplates for use onprofiling machines to guide the cutters thereof. Mypinvention overcomesthe necessity of such machine work and eliminates the expensiveprofiling operation. This is accomplished by casting the tread ring 28from aluminum or a similar .metal .alloy which/can be castto therequired sizewith 'the necessary projections and depressions formedintegra therewith for molding the tiretread. Aluminum and varying alloysthereof, such as used in making diecastings, can be cast in such a waythat its surface is for all practical purposes just as smoothl as thatproduced by a machined mold.

' The tread ring 28, if desired, Amay be cast in one continuous ring orit may be made up of .a plurality of segments. When the ring .is madeinsegments I preferably provide a steel shell 32 having flanges 34 and36 embracing the side walls of the tread ring. This steel shell hassecured to one 'edge thereof a locating b1ock'35 which is adapted toengage a slot.36 in the ring 10 when the. mold is assembled. Extendingradially in- `Ward from the flanges34 ofthe steel shell are a 'series ofprojections 3 8 which yare spaced angularly the same distance apart asthe .side pieces 26 of the mold sections 10 and 12.' The projections 88and side pieces 26 are held in register with one another by.

v'mold sections 10 and 12, as will be readily appreciated.

To securethis relationship or any other desired relationship between theside piecesI on the 'respective mold sections I provide a same can alsohe usedJ 'for moldingf balloon dovvel 48 secured vto ene seetien which-is adapted to enter a slot 50 in the other seo- 'tion.

While l have illustrated; e mold for shaping the tread or a solid tireit is not to 1oe inferred that l ein limited thereto, as the and regularstyle pneumatic tire casings.

While l have described with greet partieularity the construction of thespecirio mold illustrated and the method. (ft-#forming parts thereof bycasting them to shrine instead of machining them, .it is not to lbeconstrued that l am limited thereby, as various modiioations may he madeWithout departing from the invention as defined in 'the eppendedelairns.

What ll oleirn is:

1. A tire mold includinga rings of relatively tough metal having dieoestside pieces secured at peripherally spaced intervals to each of saidmold rings,

a supporting shell adapted to be clamped hetvveen the mold rings and anunmaehined east treed ring secured to said shellv and having integralprojections end ldepressions adapted toserve es a mold for the treadsurface of the tire.

2. A tire mold including top and bottom mold rings of relatively toughmetal, die cast inserts secured at spacedI intervals .to each of saidmold rings and adapted to serve as cores 'for depressions in the tires'orinedin lthe mold, a supporting shell having in- Wardly extendingflanges which engage sai side pieces in' the assembled mold and annnrnaohined die cast tread ring seeuredto said shell between saidflanges, said tread ring being provided with projections and depressionsproportioned to produce the. .detop 'and bottom sired oonliguration oftire 'tread design.`

'ln Witness whereof l have hereunto signed my name..

HARRY lWllLLSHAl/V.

